Recently, an X-ray computed tomography apparatus capable of performing so-called CT fluoroscopy has come on the market. CT fluoroscopy is a technique of reconstruction and displaying tomograms in real time concurrently with a scan. CT fluoroscopy is effective for catheterization. CT reconstruction includes a very large number of processing steps. In current CT fluoroscopy, the field of view in the body axis direction is only about 6 mm (see FIG. 13). It is possible to expand the fluoroscopy range up to, for example, 32 mm by increasing the slice width of each slice. Increasing the slice thickness will make a partial volume phenomenon more noticeable and blur the tip of a needle or catheter. This makes it impossible to use an X-ray computed tomography apparatus for catheterization and the like.
A recent wide area detector includes, for example, 320 arrays (320 segments).
However, the fluoroscopy range that allows CT fluoroscopy is still limited by the reconstruction processing speed. As shown in FIG. 14, CT fluoroscopy does not effectively use many segments.
Currently, therefore, it is not possible to practically apply an X-ray computed tomography apparatus to a situation that requires instantaneousness and a wide field of view as in the case of catheterization and the like. Even if advances in reconstruction techniques will allow to reconstruct several hundred slices in real time, it is necessary to continuously irradiate a wide range with X-rays. This leads to the problem of exposure.